Abstract Children with poor early language skills are at risk for academic, social, vocational, and health challenges across the lifespan (Botting & Conti-Ramsden, 2008; Conti-Ramsden, Durkin, Toseeb, Botting, & Pickles, 2017; Norbury & Sonuga-Barke, 2017; Pace, Alper, Burchinal, Golinkoff, & Hirsh-Pasek, 2019). This at-risk group includes approximately 1.6 million children under five with primary developmental language disorder (DLD) and 300,500 children with DLD and an autism spectrum disorder (ASD+DLD; Bishop, 2010; Norbury & Sonuga-Barke, 2017; U.S. Census Bureau, 2017b; Xu, Strathearn, Liu, & Bao, 2018). Parent-implemented early language intervention is a cost-effective option to address this public health issue. However, these interventions yield large individual differences in outcomes and limited scalability (Roberts & Kaiser, 2011). Variable intervention effectiveness could result from many factors including parent-level differences in language skills and behavioral awareness. Despite differences in interaction quality across parents (Hirsh- Pasek et al., 2015), and potential heritable components of language disorder (Bishop, 2009), there has been little to no exploration of the role of these parent-level factors in early language interaction and intervention. This project will address this critical gap in the evidence. Parents' language skills will be examined in relationship to the quality of parent?child language interactions (Aim1). Furthermore, this research will explore whether parents' behavioral awareness predicts their modifiability after brief training (Aim 2). Finally, predictors of early language interaction quality and modifiability will be compared in dyads with typically developing children, children with primary DLD, and with ASD+DLD (Aim 3). The long-term goal of this research program is to increase intervention effectiveness and improve child outcomes by extending the social-interactionist framework to scaffold parents. Differences between the DLD and ASD+DLD groups could inform disorder- specific intervention recommendations. Behavioral data will be collected from three groups of parent-child dyads?children with primary DLD (Aim 1,2,&3), children with ASD+DLD (Aim 3), and age-matched controls (Aim 1,2,&3). Inter- and intra-group analyses will be conducted to explore the relationships between parent- level factors, the quality of parent?child interaction, and parent modifiability following parent training. These aims will support the long-term career development goal of improving the language, academic, and health outcomes of at-risk children through family-centered early language intervention research. Three specific areas of career development have also been identified: 1) examining individual-level factors that impact early language interaction and intervention outcomes, 2) applying family-centered intervention to specific disorder groups, and 3) analyzing multi-level and longitudinal data. The career development will take place at an R1 university with support from an accomplished, inter-disciplinary mentorship team.